The concept of utilizing squish jets in combustion chambers to increase turbulence of the air fuel mixture withing the combustion chamber is known. One of the most recent designs wherein squish jets (for air or air fuel mixtures) are directed into a bowl in a manner to increase the turbulence of the air fuel mixture, particularly within the bowl, by interference between jets is disclosed in U.S. Pat. No. 4,572,123 issued Feb. 25,1986 to Robert L. Evans. In this patent passages are formed through the piston (or cylinder head) from a compression face to discharge into a bowl at locations above the base of the bowl, i.e. between the rim and base of the bowl,the rim being substantially in the plane of the compression face. The air fuel mixture is forced through these passages by the piston movement within the cylinder particularly as the piston approaches the top dead centre position and is driven from the passages to issue as jets into the bowl. The jets are aimed to interact to increase the turbulence of the air fuel mixture in the bowl.
In the arrangement shown in the patent, the passages are tubular and thus are difficult to construct.